BaMaTech DuoBand-Feed: receive poor?

G8KWX The first generation of bamatech feeds was linear poralization. This should be the difference you see on SDR Console.

POTY is the Patch Of The Year, which the Bamatech antenna is NOT.

G8KWX

Hi,

similar observations here.

Did some experiments with an original LSP-02G and my BaMaTech feed WITH dielectric lens.

Difference is about 5dB here.

I think the BaMaTech feed couln't be mounted with optimum focus because of the big reflector of the 2.4GHz feed.

73, Thorsten

Until now, i am also not happy with my duofeed Bamatech. It has been reportet to me there is as lnb a Opticum LSP-02G in use. I ordered two of them to investigate about the sensitivity, modification etc. Also I like to compare it with other different brand lnb. I opened one of the Opticum without problems and checked the possibility about the modification with a external TCXO.

First of all I installed the second Opticum LSP-02G to my 85 cm offset dish and carefully pointet it to the QO-100. The result with this lnb has been very bad, it jumped very strong with the frequency. See my screenshot from the SDR console.

Next step has been to install a Megasat Diavollo Twin.

After that I install a Single lnb GM-201 and carried out the test.

Finally I install the Bamatech Duo Feed with included Opticum LSP-02G and testet the sensitivity.

From all testet lnb this produce the weakest signal compared to the others bevor. Bamatech selected the lnb against wobbling this shows the nr. at the bottom and this lnb was not wobbling. But with this bad sensitivity it will be not possible to use it for good contacts via QO-100. The lnb with the best sensitivity is the GM-201 with clear and strong signals.

At a other place at this forum we discuss bevor the possibility to change the Opticum LSP-02G but we found no solution how to do it. In the moment I have no ideas how to overcame this problem.

Quote from G8KWX

I now assume that the LSP-02G is meant for center fed dish ?

I would say no, i would assume most of the use cases for TV reception are for offset dishes.

I use a multifeed configuration with the QO-100 feed 2.2° out of focus and the Astra feed about 4.5° out of focus.

The waveguide at the unmodified LNB seems to be a bit better in a direct comparison.

The BaMaTech duoband feed is just a compromise, if you want to have a compact, mechanically well solved and good working solution I would say.

I am currently experimenting to feed the BaMaTech LNB with 24MHz instead of 25MHz. I am curious, if the LNB works better at about 1.1GHz IF. Maybe that's a way to get out the last dB...

Quote from DJ7WL

Finally I install the Bamatech Duo Feed with included Opticum LSP-02G and testet the sensitivity.

Uuuh, that' really a big difference to the GM-201.

That's my spectrum at a Kathrein CAS80 with 0dB additional gain of my RTL-SDR...

Edit:

Just a note: Feeding the LSP-02G with external reference of 25MHz (from the new Amsat Downconverter) brought nearly 8dB more S/N than with my TCXO modification...

DL9SEC

This looks quite similar to the GM-201, thats what we like to see.

G8KWX

either two dishes, alternative you may use a POTY.

DL9SEC

on what way you feed the reference frequency into the single lnb LSP-02G?

Quote from DJ7WL

DL9SEC

on what way you feed the reference frequency into the single lnb LSP-02G?

This way: 25MHz external reference modification for the Opticum LSP-02G/Robust LNB

Quote from DJ7WL

G8KWX

either two dishes, alternative you may use a POTY.

I can not see the real advantage using the POTY, because the 10GHz feed is very similar to that of BaMaTech.

Maybe a solution with a standard LNB and a helix could be better for you...